1. Field of the Disclosure
The present invention relates to seat structures, and more particularly, to seat structures that are switchable between a chair form and a bed form
2. Description of Related Art
FIGS. 10 and 11 illustratively show an example of seat structures switchable between a chair form (FIG. 10) and a bed form (FIG. 11). The seat structure includes: a seat main body 1; a seating surface element 2 attached to the seat main body 1, and extending in a longitudinal direction; a back element 3 connected to a rear end of the seating surface element 2 in a reclinable manner, and extending in a vertical direction; and an upper end flap (a head guard) 4 connected to an upper end of the back element 3 in a forward tiltable manner. In the chair form of FIG. 10, the upper end flap 4 is located in substantially the same plane as that of the back element 3. In the bed form of FIG. 11, the upper end flap 4 is tilted forward and lifted with respect to the back element 3.
Such a seat structure is disclosed in, e.g., Japanese Publication No. 2007-55462 of unexamined patent applications. Japanese Publication No. 2007-55462 of unexamined patent applications discloses a baby carriage that is switchable between a forward facing state where an infant sitting in the baby carriage faces forward, and a rearward facing state where the infant faces rearward so as to face a person pushing the baby carriage. This baby carriage is preferable in terms of safety, because the upper end flap 4 covers the top of the head of the infant sitting in the seat when the seat of the baby carriage is switched to the bed form.
The seat structure of the baby carriage disclosed in Japanese Publication No. 2007-55462 of unexamined patent applications has a lifting mechanism for lifting the upper end flap, in addition to a reclining adjustment mechanism for the back element. The lifting mechanism includes a rotation member, a rod bar, and inhibiting means. The rotation member is provided on the back surface of the back element, has its center movable about the rotation center of the back element, and is rotatable about the center of the rotation member itself. The rod bar connects the rotation member and the upper end flap. The inhibiting means inhibits rotation of the rotation member when the tilt angle of the back element reaches a predetermined value. While the back element is being tilted toward the predetermined tilt angle, the rod bar is pressed toward the rotation member by an urging force of urging means, and the rotation member is rotated about its center, whereby the upper end flap extends in the extending direction of the back element. When the tilt angle of the back element reaches the predetermined value, rotation of the rotation member is inhibited, and the rod bar lifts the upper end flap with respect to the back element against the urging force of the urging means.
Since the lifting mechanism for the upper end flap disclosed in Japanese Publication No. 2007-55462 of unexamined patent applications has a somewhat complex structure, a simpler structure is desired.